A comparison of chemical and physical methods for treating French fries to produce an acceptable microwaved product

Frozen par-fries were processed in January and February using BelRus and Russet Burbank potatoes which were obtained from the same source and held under the same storage conditions. Prior to par-frying the raw potato slices were treated chemically or physically in order to increase the amount of bound water, or to remove water. At each processing date total solids of the raw and treated tissue were determined. Par-fries were analyzed for fat content. Treated samples were microwave heated and evaluated for sensory qualities as compared to frozen par-fries heated in a conventional oven. In no cases were the microwaved fries superior to the oven-heated fries in color, flavor, or texture. Drying the blanched fries in an oven for 10 min. prior to par-frying produced a microwaved product that was quite similar to the oven-heated fries, particularly in the case of the BelRus potatoes. In all cases BelRus potatoes absorbed less fat on par-frying than did Russet Burbank potatoes.     

Infection of plant material derived from Solanum acaule with Clavibacter michiganensis ssp. sepedonicus: temperature as a determining factor in immunity of S. acaule to bacterial ring rot

The development of potato ( Solanum tuberosum ) cultivars immune (completely free of infective agents) to bacterial ring rot disease, caused by Clavibacter michiganensis ssp. sepedonicus , would be a significant step toward eradication of the disease. Earlier results suggested that the wild potato species Solanum acaule , acc. PI472655 (genotype 7-8), was immune to C. michiganensis ssp. sepedonicus . The goal of the present study was to investigate the possibility of transferring this desirable trait to cultivated potato through interspecific somatic hybridization. Eight different somatic hybrids between S. acaule and S. tuberosum , with three different genome ratios, were tested for susceptibility to infection in the glasshouse using two C. michiganensis ssp. sepedonicus strains. All the somatic hybrids expressed symptoms of ring rot and were susceptible to infection as determined by IFAS (indirect immunofluorescent antibody staining) tests. The genome compositions of the hybrids influenced bacterial titres. Most of the hybrids with a higher proportion of the S. acaule genome contained lower numbers of C. michiganensis ssp. sepedonicus cells than hybrids with lower proportions of the S. acaule genome. In growth chamber tests, temperature was found to be a determining factor in the expression of immunity in the tetraploid S . acaule 7-8 line. At 21°C, S . acaule 7-8 was immune to infection by C. michiganensis ssp. sepedonicus , but at 15°C, plants supported large populations of the pathogen. However, none of the S. acaule plants expressed disease symptoms. Thus, S. acaule exhibits temperature-dependent immunity to infection by C. michiganensis ssp. sepedonicus and should be considered tolerant rather than immune.     

Quantitative assessment of fungal colonization in Norway spruce after green pruning

In July and in October of 1978, 1979, 1980 five Picea abies stands in Baden-Württemberg, Germany were green-pruned up to a tree height level of c. 10 m. In 1993–94, 30 pruned trees and five control trees from each stand were harvested for investigation. The quality of pruning proved to be excellent because only few branch collar, bark injuries or too long branch stubs were detected. Based on isolations from more than 6000 wood specimens of c. 20 mm³ obtained from 175 trees, specific infection rates are given for different tree compartments. Wood decay fungi as well as important blue stain fungi were only rarely present. Tolerable discolourations were limited to the stub containing core of a few trees. Wood formed after pruning showed neither more fungal infections nor other related disadvantages compared with the respective increment from unpruned control trees. Nectria fuckeliana, proved to be the most abundant fungus in pruned trees especially in the branch stubs. Respective infection rates in and close to dry branches were compared. Bacteria could be found in the pruned branch stubs, however, they did not penetrate into the heartwood or sapwood of the stems. Both summer and autumn pruning involve only very low risk of wood deterioration. However, summer pruning shows some advantages with respect to lower infection rates by N. fuckeliana.     

Detection of quantitative trait loci in Pinus sylvestris L. across years

In an earlier study, we reported the characterisation of quantitative trait loci (QTLs) for economically important traits related to wood production for a specific year of measurement. However, validating the detected QTLs across years is important for any strategy for marker-assisted selection (MAS). Therefore, we evaluated the consistency of the QTLs across four years in 9 to 12 year-old trees. Data related to tree height were analysed in two ways. The total height was used to characterise QTLs likely to be useful in MAS, and the increment values to evaluate growth regulation. Among the 11 QTLs detected, 4 were found in both the 1996 and 1997 evaluations. QTL numbers and locations related to total height were found to be highly stable. However, the QTL effects progressively changed in successive years, following either an increasing, decreasing or curvilinear trend. Depending on their specific trends, some QTLs may not be expressed at all later in maturity, or they may be expressed at a higher level. This will have direct consequences on the applicability of molecular markers in early screening programs, since a study at the mature stage may also be required. More variation in QTL number and effect was observed relating to height increment than to total height, indicating significant differences in gene expression during the growth periods involved. This revised version was published online in August 2006 with corrections to the Cover Date.     

Combining ability of cassava genotypes for cassava mosaic disease and cassava bacterial blight, yield and its related components in two ecological zones in Ghana

Breeding for resistant genotypes is the best strategy to offset the destructive effects of cassava mosaic disease (CMD) and cassava bacterial blight (CBB). Two sets of diallel parents were selected for the forest and the savannah ecological zones in Ghana based on good levels of resistance to CMD and CBB. Both sets were crossed in a half-diallel design. The first set of seven progenitors and their 21 F1 progenies were planted in a randomised complete block design (RCBD) with three replications in two different locations for two seasons in the forest ecology. The second set of five progenitors and their 10 F1 progenies were planted in a RCBD with three replications in two locations in the coastal savannah ecological zone of Ghana. Both experiments were evaluated for CMD and CBB resistance, fresh root yield, dry root yield, root number, harvest index, dry matter content, plant height at maturity and height at first branching, levels of branching and plant vigour. Results of the combined analysis of variance revealed that the environment effect was significant for all the traits. General combining ability and specific combining ability effects were significant for most of the traits. Narrow sense heritability was significant for plant vigour, root number, CMD and CBB in both the zones. CMD and root number also had a predictability ratio of close to one, indicating the importance of additive gene effects.     

Differential response of cocoa (Theobroma cacao) families to field establishment stress

High seedling mortality during the establishment phase of cocoa has become a critical constraint to sustainable cocoa farming. The objective of this study was to develop varieties with higher seedling survival compared with cultivars currently recommended for planting in denuded regions. Thirty‐seven families composed into two sets of 18 (families from recommended clones) and 19 (families from recently introduced clones) were evaluated for field survival under full sunlight and dry weather conditions. Families differed significantly for vigour (increase in trunk cross‐sectional area, TCSA) and percentage of survived seedlings by the end of the dry weather conditions. Survival and vigour were significantly correlated in only one set of families. The contribution of general combining ability (GCA) to seedling survival was low to moderate. An Amelonado clone and clones from the Iquitos genetic group had negative GCA estimates for both increase in TCSA and survival. Clones of Scavina origin had the most positive contribution to survival. The key outcome of the study was that cocoa families with higher establishment success can be obtained from the currently available germplasm.     

Seed-setting in potatoes as affected by spraying with a-naphthaleneacetamide and by light

American Journal of Potato Research - Spraying potato plants with dilute concentrations of a-naphthal-eneacetamide was not effective in increasing flower or seed ball production in the greenhouse...     

Apparent Tolerance of a Field-Collected Strain of Myzus nicotianae to Imidacloprid due to Strong Antifeeding Responses

A French strain of the tobacco aphid Myzus nicotianae Blackman (Homoptera: Aphididae), strain FR, showed high tolerance to imidacloprid in short-term (48-h) oral ingestion bioassays when compared to a susceptible reference strain of Myzus persicae, strain NS. The resulting tolerance factors were >50. Measures of the contact activity of imidacloprid by the FAO dip method failed to detect these high factors of tolerance. The tolerance factor was in general <10 when using the dip method. The resulting difference between tolerance factors could be attributed to a behavioural component to fitness between strain FR and strain NS as further experiments revealed. When measuring the effect of systemically applied imidacloprid on honeydew excretion, a 50% reduction occurred in both strain FR and strain NS at nearly the same concentration of imidacloprid, providing evidence for a similar antifeedant response in both strains. Starvation experiments revealed that the French strain was able to survive approximately 24 h longer than a reference laboratory strain of M. persicae. This result coincided with the fact that systemically applied imidacloprid showed the same aphicidal potential against strain FR after three days as against strain NS after two days, i.e. 24 h later. After rearing in the laboratory for six months the French strain of M. nicotianae lost its hardiness and also its apparent ability to tolerate imidacloprid. However, strain FR was a heterogeneous field strain and it is possible that a susceptible variant out-reproduced a more hardy variant. These findings indicate that the type of bioassay is very important when assessing aphid populations for resistance against the chloronicotinyl insecticide imidacloprid, because of its distinct mode of action. It is obvious that an aphid dip test, i.e. FAO dip test, produces more reliable results than the different kinds of short-term oral ingestion bioassays, because of the reversible behavioural changes induced by imidacloprid after oral uptake. Thus a short-term oral ingestion bioassay (≤48 h) is not recommended for precise detection of possible resistance of Myzus sp. to imidacloprid, although this mode of uptake for imidacloprid might be sometimes more realistic in terms of field behaviour. The ideal test to generate most accurate data would be a slightly longer (72-h) feeding bioassay, perhaps used in conjunction with a dip test. The possible influence of the results on resistance monitoring is discussed. © 1997 SCI.